Reciprocating motor



March 18, 1941.

K. G. STBERG 2,235,586

nncrrnocnme MOTOR Filed July 18, 1939 2 Sheets-Sheet l '-1 jy- 14 57 4J J/ Ja i 5 jif5 :T T: ,y 4 4@ 2l Q @o w UTE?? d I g 2a 5 7 /0 g f, ln

"/ [Wye/2@ 4 5f @Ms/Z kl A March 18, 1941.' i K Q STBERG l 2,235,586

RECIPROCATING MOTOR Filed -July 18, 1939 2 Sheets-Sheet 2 Patented Mar. 18, 1941 vPATENT OFFICE RECIPROCATING MOTOR Karl Gustar* stberg, Stockholm, Sweden, as-

signorA to Fabriksaktiebolaget Haldataxametern, Halmstad, Sweden, a company of Sweden Application July 1s, 1939, serial No. 285,210

In Sweden July 28, 1938 v5 ciaims. (ci. 121-164) The present invention relates to driving mechanisms for machines or the like having an intermittent or reciprocatory movement, such as plate shearing machines, nibbling machines, presses,

5 punching machines, forging hammers or the like. More particularly the invention relates to driving mechanisms of the kind set forth which comprise a cylinder havingan inlet and an outlet for a A pressure medium, a piston movable in said cylinder, and a valve for controlling said outlet, said valve being adapted to be held in closed position by the pressure in the cylinder and to be moved to open position by the piston during its return movement.

15. It is an object of the invention to provide an improved driving mechanism of said kind which is simple of construction and eflcient and reliable of operation. With said and other objects in View a driving mechanism has been provided according to the present invention in which said controlling valve is coupled with the cylinder so ythat the valve is opened by the piston striking Iagainst an abutment on the valve at the end of the stroke and is restored to closed position by the piston during the return movement of the latter, for instance under the action of an auxiliary force, by way of example by spring power. The driving medium advantageously consists of oil or some other liquid preferably driven to the cylinder by means of a continuously operating compressor or the like, a practically constant stream of liquid being then supplied to the cylinder at 'the inlet side. The operating speed then becomes approximately inversely proportional to the length off the stroke which preferably is adjustable.

The invention will now be described more in detail having reference to the drawings-attached to this speciiication and forming part thereof. vln

40 the drawings, which show an embodiment adapted more particularly to be used in plate shearing machines or the like, Figure 1` is a side view and partly a vertical section of the mechanism,and Figure 2 a front view. I

The cylinder I is carried by a frame 2 and provided with a detachable cover 3 which is'secured to the cylinder by means of screws and secured also directly to the frame. Movable in the cylinder I is a ring-shaped piston 4 which rests loosely on a circular plate 5 forming the upper extended end of a hollow piston rod 6, which passes through a lining I provided in the cylinder cover 3, said hollow piston rod carrying at its lower end a square holder 8 for one cutting tool 9v of 'a plate shears the other cuttingtoollof which is inserted in a lower cutting tool holder I I which is rigidly secured in the frame 2. The piston rod is effectively guided by the movable cutting tool holder 8 engaging with a guide I2 provided in the frame. 5

In the present embodiment the driving mechanism is assumed to be hydraulically operated, oil being preferably used as a pressure medium, said oil being preferably driven in a closed circuit by a continuously operating compressor or the like. `10 and being supplied to the cylinder at the inlet I3 and returned to the compressor through the outlet I4. The outlet is controlled by a valve I5 which is coaxial with the piston, the lower cylindrical portion of said valve fitting into the ring- 15 shaped piston 4 so that the valve will be movable axially with respect to the piston. Secured by means of screws to the upper side of the piston is a ring I5 the inner edge of which overhangs an annular ange I1 on the valve I5. The ring- 20 shaped space immediately below the iiange I'I is filled with pressure medium, so that when occupying its closed position, as shown in Figure l, the valve is held forcefully pressed against its conical valve seat I8 because of the fluid pressure 25 on the underside of the ange Il.

Figure 1 shows the various parts of the driving mechanism in the positions which they occupy when the piston is prepared to begin its downward stroke under the action of the hydraulic pressure 30 acting on its upper side. In this position of the parts the underside of the valve I5 is engaged by a circular plate I9 which by means of a helical spring 20 disposed within the piston rod 6 is held pressed against six spacing pins 2| passing freely 35 through corresponding holes in the plate-shaped upper part 5 of the piston rod and resting at their lower ends on a nut 22 which is threaded on to the piston rod. With the underside of the nut engages the upper end of a powerful helical spring 40 23 which at its lower end engages with a ring 24 that rests on balls 25 at the bottom of the cylinder cover 3. A ring 26, which is threaded over the piston rod 6 and which is held in position on the piston rod by means of a cross pin, serves to pre- 45 vent an unintentional unscrewing of the nut 22. Around its circumference the nut is provided with a number of teeth which engage with a pinion 28 journalled on a bolt 21 between the cylinder and the cover, said pinion being provided with a 50 radially extending handle 29. By moving the handle towards the one or the other side, the nut 22 can be turned on the piston rod, thereby adjustingthe piston and the plate I9 axially withV respect tothe valve I5 for the purpose of chang- 55 ing the length of stroke which, as will be clear from the following, is equal to the distance between the lower surface of the ring I6 and the upper surface of the flange I I in the illustrated position.

In front of the cylinder there is provided between the inlet I3 and the outlet I4 a by-pass 30 for .the pressure medium which by-pass, when the driving mechanism is in operation, is kept closed by a starting and safety valve 3|. Said valve is loaded with va powerful helical spring 32 disposed in a turnable tube 33 at the -top of the cylinder and arranged under tension between the bottom of the tube and a movable cover 34 which during operation, as is shown in Figure .1, is held depressed by one edge of a cylinder 35 part of which is out away along la plane that is parallel with its axis, said cylinder being journalled cross-wise in the upper part of the tube 33 and being provided with a bent starting rod 36. On account of the turnability of .the tube 33 the starting rod 36 can be shifted to different lateral positions.

In the fluid passage between the valve I5 and the outlet I4 there is furthermore inserted a lifting valve 3l' which is loaded by a comparatively weak spring, said valve serving only to increase the pressure on the upper side of the main valve I5 upon 4the opening of said valve in order thereby to accelerate the complete opening of the valve. Generally there is produced at the same time, however, on account of the acceleration of the body of liquid in the return conduit leading to the compressor, a suiiicient counterpressure so that in most cases the .auxiliary valve il is unnecessary and may be dispensed with.

The mechanism operates in the following manner.

As soon as the main valve I5 has been. closed by the piston during the upward movement of the same caused by the spring 23, the pistonimmediately starts its down-stroke under the action of the high hydraulic pressure produced upon the closing of the valve. The movement of the piston continues until the ring i6 strikes against the iiange I'I of t-he Valve |75, opening said valve, the piston then stopping on account of the lowering of the pressure, whereas on account of the increased pressure on its upper side the valve will be flung down against the plate I9 connected with `the piston. The pressure on the upper side of the piston is then further reduced and the piston is lifted by the spring 23, the piston then bringing along lthe valve I5. At the end 0f the stroke of the piston .the closing ofthe valve will be accelerated because of Ithe suction from the liquid flowing back through 4the return conduit. The operation is then repeated in the same manner. The driving-mechanism is stopped by pulling down the starting rod 36, the starting valve 3l being then opened, offering a free passage for the pressure medium past the cylinder.

As will be clear from the abovethe length of the stroke of `the piston is determined by the size of the space betwen the ring I6 and the ange II when the piston occupies its uppermost position, the stroke being equal to thewidth of said space. I-t will thus be possible to regulate the length of stroke by raising or lowering the working piston with respect to the valve I5 when in closed position by means oi the regulating mechanism described, consisting of the spacing pins 2l, thenut 22, and the pinion 28 provided with the handle 29. If the iiow of liquid to the inlet I3 is constant the number of strokes per second will be approximately inversely proportional to the length oi' stroke, as .already mentioned. The space below the piston 4 is in communication with the atmosphere.

I claim:

1. A reciprocating motor comprising in cornbination, a cylinder provided at one end with an inlet for pressure medium and with an outlet arranged Acoaxially with respect to the cylinder, a piston movable in said cylinder, a valve body for controlling said outlet journalled coaxially in a central recess of said piston so as to be movable axially with respect thereto, an `abutment on the piston restricting .the axial movement of the valve body relatively -to the piston in one direction, a. stop member connected with the piston and shiftable in axial direction, said stop member serving to restrict said relative axial movement in the other direc-tion, and means tending to move the piston towards the outlet end oi the cylinder into a position in which the `outlet is closed by said valve body and the length of stroke of the piston being substantially equal to the length of axial movement of the valve body relatively to the piston and being variable by adjustment of said shiftable stop member.

2. A reciprocating motor. comprising in combination, a cylinder provided at one end with an inlet for pressure medium and With an outlet arranged coaxi-ally with respect to the cylinder, a piston movable in said cylinder, a valve body for controlling said outlet journalled coaxially in a central recess of said piston so as to be movable axially with respect thereto, an abutment on the piston restricting the outward axial movement of the valve body relatively to the piston, spacing outer ends of said spacing members in contact l with said annular stop member, said spacing members and. said annular stop member cooperating to determine the bottom position of the Valve body in said central recess, and means tending to move the piston towards the outlet.

end of the cylinder into a position in which the outletis closed by said Valve body and the length of stroke of the piston being substantially equal tothe length of axial movement of the valve body relatively to thepiston and being variable byl adjustment of said shiftablestop member.

3. A reciprocating motor as claimed in claim 2, in which said adjustable annular stop member consists of a nut threaded onto the piston rod and provided at its circumference with teeth eng-aging a pinion.

4. A reciprocating motor comprising in combination,.a cylinder provided at one end with an inlet for pressure medium and with an outlet arranged coaxially with respect tothe cylinder, a continuously Operating `compressor driving a constant stream of.' pressure medium to the cylinder, a by-pass provided in parallel with `the passage through said outlet, a valve normally closing said by-pass, means for operating said byvpass valve, -apiston movable in said cylinder, a

tion in which lthe outlet is closed by said valve body and the length of stroke of the piston being substantially equal .to the length of axial movement of the valve body relatively to the piston and being variable by adjustment of said shiftable stop member.

5. A reciprocating motor `as claimed in claim 4,

.in which said by-pass valve is loaded with a spring tensioned between said valve and a suppont which is shiftable so that the valve can serve simultaneously as a safety valve and a starting valve.

KARL GUSTAF OSTBERG. 

